1. Field of the Invention
The present invention relates to built-up screens, and more particularly relates to a built-up screen coupling structure in which each two screen board frames are coupled together by a plurality of fastening devices and reinforced by an adjusting device.
2. Description of the Prior Art
FIG. 1 illustrates a built-up screen coupling structure according to the prior art, in which the first screen board frame has a " " shaped lock pin 2' fastened in a " " shaped slot on the second screen board frame for connection. Because the slot and the lock pin are both designed in " " shape, i.e. in angle structure, only one set of slot and lock pin can be made on the screen board frames at a lower position. If two or more sets of slots and lock pins are respectively made on the two screen board frames, the connection of the slots with the lock pins will be very difficult to achieve. Because there is only one lock pin on the first screen board frame for locking in the slot on the second screen board frame, the connection of the two screen board frames is not very stable. Further, the stands which support a built-up screen are generally connected to the screen board frames of a built-up screen by screws which are generally fastened through the face panel. Because the head of the screws is disposed visible on the face panel, the sense of beauty of a built-up screen is somewhat destroyed. When two screen board frames are to be connected together in 90.degree. angle, a connecting frame A is commonly used. After connection, as shown in FIG. 10, the connecting frame A must be covered with a cover plate D so that a smooth and beautiful top surface can be obtained on the built-up screen. The cover plate D has a plurality of stub tenons D1 at the bottom respectively inserted in a plurality of stub mortises A1 on the top of the connecting frame A. This tenon-and-mortise connection can not fixedly secure the cover plate D to the connecting frame A once the cover plate D is pushed upward by an external force. Referring to FIG. 11, there is illustrated a supporting plate connected to a screen board frame for supporting a table, in which the supporting plate has a plurality of unitary, hooked strips at one end and respectively hooked in a plurality of notches on a screen board frame. In this connection structure, there is no any locking device to lock up the connection of the supporting plate with the screen board frame, and therefore, the supporting plate may be easily detached from the screen board frame or get loosened.